GB2228695 discloses an internal turning tool having a hook tool clampable in a receiving recess of a clamping holder. The receiving recess is provided with clamping surfaces which converge radially outwards from a longitudinal axis of the receiving recess. A chucked end of a shaft of the hook tool is provided with a radial projection projecting from the periphery of the shaft. The projection has outwardly converging abutment surfaces formed to abut the clamping surfaces of the receiving recess. The hook tool is also provided with a coolant bore formed internally within the radial projection.